Stack control



Feb. 2, 1932. l -,J. RYAN STACK CONTROL Original Filed April 15. 1927 Patented Feb. 2, 1932 FREDERICK J. nYAn, on rn fannnrnia, rnn'nsrfivan'rn, essienon To no. .RYAN

AND CGMPANY, or rn nenntrrfra, rnnnsrnvenra, a oonronarron or DELA- WARE STACK ooirrnon I Original application filed April 15, i927,Seria1:XIo. 184,132. Divided and this application filed April 23, Y 1929. Seria1No.357,526.

This application is a division of my co pending application, #18,132, filed- Apr l.

stacks, the size of which is suificient to handle a the maximum capacity of the furnace. Very seldom, however,is the furnac-eoperated at 7 its maximum capacity, so that during the ordinary operation, the ventsare attempting to exhaust a greater volume of gases than that which is delivered in the'ordinary manner into the furnace; This tendency of the vent or stock to exhaust more than 'a suflicient supply of gas is especially noticeable in a furnace employing an. automatic control such as that illustrated inm'y copending'application, in whichis disclose'dan equipment which functionsautomatically in turning on and off the supply of fuel and air to regulate the temperature; =Forexample, furnace employing a control according to my copendingapplication may have been working at maximum capacity, approximately 3000 cubic feet of hot gases -being vented per minute. If now, the furnace has reached a temperature of say 1650 R, the automatic control valve functions to prevent a temperature greater than that, accomplishing this result'by cutting down the delivery ofair and fuel approximately to 40%. Assuming thereduction to be 30%, it can bejreadily seen that about .900 cubic feet of gaseshave been dropped from the total volume supplied. This diminution'in quantity is prac tically instantaneous, and occurs ata time when the stacks are operating at full capacity. t k

If at this time, the" furnace wer'etightly sealed up, with the exception of the'suction passage, the velocity of gases passing out Wardly through the, stack would be immediately diminished .greatly what actu-.

ally occurs, however, is'that the velocity or suction is still great enough to compensate for. the pressure loss by drawing inexcess air around the burner ports and through the cracks in the furnace walls. This action results in oxidation or scaling of the material to be treated, as well as the elements of the furnace, and at the same time reduces what I term the furnace pressure. By normal furnacepressure is meant that the percentage of hot gases Within the heating chamber vof in dustrial heating furnaces are at all times sufficient to prevent any uncontrolled intake of into thefurnace as a result of a'low pressure area therein, y I By my invention, the controlsystem of my (so-pending application is properly correlated with the stack'control therein, so that upon diminuation of the fuel and air supply to the furnace, a corresponding reduction in the effective stack 0138111119 will take place at the same time. By'this' means, since the total quantity of gases passed out through the stack per unit of time will be diminished, the pressure in tl e furnace will be maintained substantially constant, preferably at a slight excess of the critical or normal pressure previously referred to, so that there will be no tendency for decrease in the furnace pressure and consequent detrimental action of the incoming air on thetniateria-l being treated.

An object of the invention, therefore, is to produce an efficient heat treatment of thema} means for maintaining the temperature in the furnace substantially constant, for maim tainingthe pressure conditions in tl e furnace substantially at apredetermined value. .1 I

Still another object is to device apparatus for a furnace formaintaining the pressure therein ata constant value, slightly in excess of that required to prevent the entrance of air through uncontrolled openings into the furnace.

Yet another object is to prevent oxidization of the material being treated as well as the elements of a furnace, during the heat treatment of the said material in the furnace.

Other objects will appear hereinafter.

One form of my invention is shown in the accompanying drawings by way of illustration wherein,

Fig. 1 is an elevation showing the various inter-related connections to the furnace, which latter is shown in vertical section, while Fig. 2 is an enlarged view of the control mechanism of Fig. 1.

In the drawings, a furnace 1 of conventional design is shown as having an inner chamber 2 and an outer enclosing furnace chamber 3. The outer chamber 3 is provided with a lower combustion portion 4 having an opening 5 :for an oil burner 6 or other heating apparatus. The combustion chamber 4 extends into engagement with a hearth 7 which constitutes a bottom wall for the'inner furnace chamber 2. The hearth may support, as shown, a material 8 which is to be treated. The upper walls 9 and 10 of the inner and outer furnace chambers 2 and 3, respectively,,are provided with substantially aligned outlet openings 11 and 12 for the furnace gases. The outlet opening 12 for the outer furnace chamber 3 is extended by means of a stack 13 having therein a control valve 14, which is connected by linkage 15 to an air operated motor 16, the linkage 15 having a counterweighted lever 17 tending to hold the stack valve 14 in its normally closed position. The valve 14 may be so adjusted, however, as to insure a desired minimum passage of gases through the stack 13 from the furnace 1.

The burner 6, which may take the form of that disclosed in Patent #1,161,183, issued November 23, 1915, to George F. Beach, is connected by means of an oil feed line 18 to an oil valve 19 constituting one element of a valve group 20. The oil burner 6 is also connected by anair pipe 21 to an elongated casing 22 having a butterfly valve or similar mechanism 23 which constitutes another ele ment of the valve group 20. The air motor 16 is connected by an air pipe 24 to a pilot valve 25 which constitutes still another element-of the valve group 24. Air is supplied to the valve 25 by means of a supply pipe 26 leading to a main air supply pipe 27. One end of the pipe'27 may be connected to an air blower, (not shown) while the other end is connectedto the casing 22. The valves 19, 23, and 25 may be operated by a mechanism such as the yoke-shaped member illustrated at 28, which is connected by means of a suitable armature 29'to a solenoid 30. The mechanism 28 is preferably provided with a plurality of 'ature control instrument 45.

neaaseo adjustable abutments 31 whereby desired ones, or all of said valves may be independently or simultaneously operated and ad justed.

The zero position of the air or butterfly valve 25, which may be indicated by an indicating plate 32, is preferably such that a minimum supply of air is continuously supplied to the oil burner 6, sufficient to maintain proper combustion conditions in the furnace 1, as well as the proper operation of the burner 6, when only the furnace losses are to be supplied. The .oil valve 19 is also provided with by-pass means having a control element 33 whereby sufficient oil may be supplied to the burner 6 to compensate for furnace losses. Similarly, the closed position of the stack valve 15 is such that for the conditions just stated, sufficient draft is establishedto assureefficient operation of the furnace. The construction and arrangement of the parts 19 to 33 and 16 may be substantially as illustrated in the patent to Beach, No. 1,763,385 granted June 10, 1930, for valve apparatus. and more particularly as illustrated in Fig. 7 of said patent. v

Since the specific structure of the various elements just enumerated forms no part of this invention except in the combination shown, no furtherdescription thereof is believedto be necessary.

The operation of the several parts of the valve group from the noload or furnaceheating position shown in the drawings in which the valves23 and 19are open to supply fuel and air and the valve is closed so that no fluid pressure is supplied to the .motor, to a load position in which the positions of these valves are reversed. as shown in dotted lines in Fig. 2 may beeffected by'the energization of the solenoid 30, through an electrical control circuit 34 comprising a pair of conductors 35 and 36 extending from the solenoid to an instrument panel 37. The panel 37 is also connected by leads 38 and 39 to a thermocouple or similar temperature measuring device 40, which preferably .e:-;. tends through a furnace wall 41, into engage ment with the underside 42 .of the hearth 7 The panel 37 is provided with temperature control apparatus 45 of conventional design which is responsive to variations in the leads 38 and 39 due to temperature variations in the thermocouple 40. A relay 46is also provided for the connection and disconnection of the solenoid conductors and 36 to and from the main supply circuit (not shown) in accordance with the operation of the temper- The details of these instruments constitute no part of my present invention, and therefore, will not be further described or illustrated.

It is also to be noted that certain of the constructional features of the valve group 20are not shown in detail, inasmuch as they are embodied in the co -pending application of George F. Beach, #14t7,265, filed November 19, 1926, and assigned to F. J. Ryan and Com pany. It is further to be understood that the control apparatus above described; is mere-.

ly of conventional design and maybe varied at will Without departing from the essential features of my invention. I In operation, when the temperature control instrument 45 is adjusted to the value to which it is desired to heat the material 8, currents are supplied to the, solenoid 30 through the conductors 35 and 36, causing the energization of the solenoid 30 and the actuation of the mechanism 28, the operation of which later results in the opening of the oil valve 19, the butterfly valve 23 and the pilot valve 25, the extent of opening in each instance being determined by the adjustment of the several abutments 31. Oil and air are now supplied to the burner 6 through the pipes 18 and 21, respectively, to the sub stantially full capacity of the furnace, while air is supplied to the air motor 16 to cause the opening of the stock valve 14. The increase in the amount of oil and air thus suplied to the burner 6, as well as the increase in the furnace provided through the opening of the stack valve 14, causes an increase in the temperature of the gases in the combustion chamber 4, these gases passing, as indicated, through the underside of the hearth 7 and finally discharging from the outer chamber 3 through the opening 12 and associated stack 13. The opening in the stack is now sufiiciently great to permit substantially all of the exhaust gases to pass quickly therethrough.

lVhen the temperature of the material 8 reaches and starts to exceed the desired Value, the currents generated-by the thermocouple 40, through the medium of the temperature control instrument l5 and the relay 46, cause the open-circuiting of the supply conductors 35 and 36 for the solenoid 30,

and the consequent de-energization of the latter. The operating mechanism 28 now drops from its raised operating position to its original position, with the result thatthe oil valve 19, the butterfly valve 23, and the pilot valve 25 are closed, the first two valves remaining open sufliciently to supply the furnace losses. The pilot valve 25 is so constructed that when it closes, a relief port (not shown) is open, permitting the air in the pipe 24 to be discharged to atmosphere so that the counter-weighted lever 17 may drop and return to the stack valve 14 to its original position. By thus restoring the stack valve to an approximation of its original position, the escape of a sufiicient'quantity of exhaust gases to materially reduce the pressure within the furnace is prevented.

By reason of the furnace losses,the temperature of the combustion chamber 4 and "consequently that of tlie material 8 now dropsbelow the predetermined value, whereupon the thermocouple 4&0, through. the tern-- peraturecontrol' instrument 45'and relay 46,

'again 'efiects" the connection of the conducntors 35 and 36 to" theirsource of-energy (not shown), andthereby*causes the re energizaition of 'the solenoi'd-30;" The solenoid 30 again actuates' the yolresh'aped mechanism 28 tolift it"froni its" position shown in the drawings to" its raised operating position, }ca-usingtheopening of the oil valve 19, the

butterfly valve 23 and pilot valve 25, and

stant." B'yso maintaining thefpressure at a desired value; it s "p oss1ble,'jas has' been pointed out before,- to prevent the entrance through uncontrolled orifices of any oxidizing atmosphere into the furnace interior, while by so maintaining the temperature of the material being treated and the pressure conditions within the furnace substantially constant, the product resulting from such treatment is particularly desirable, since it has been substantially unaffected by oxidizing gases playing thereover.

While the above description has dwelt almost entirely with the use of oil burners, it is obvious that the furnace might be adapted to employ coal or any other suitable type of fuel without departingfrom the essential features of my invention.

It is of course understood that the air motor 16 is shown merely for the purpose of illustrating one form of my invention, and

may be varied at will, the connections be and it is to be further understood that the invention is susceptible to numerous modifications and adaptations, it being intended that it be limited only by the scope of the appended claims.

I claim:

1. In a treating furnace, a treating chamber having an outlet stack, a damper in said stack, a fluid-pressure-operated motor to operate said damper and close the same upon admission of fluid pressure to the motor, air and fuel supply lines for said chamber, a fluid pressure supply line for said motor, valves in the air and fuel supply lines and normally open to supply air and fuel to the furnace, a normally closed valve in said fluid pressure supply line, a single member to re verse the positions of said valves and thermostatically controlled electrical means, to operate said member; s

2. Ina treating furnace, a chamber having an outlet stack, a damper in said stack, a fluid-pressure-operated motor to operate said damper and close the same upon the admission of fluid pressureto said motor,;-air andi -fuel supply lines forsaid chamben, --a connection between the air supply line and said motor, :a valve in the air supply linebetween the point of communication of said connection with the .air supply line and the chamber, a valve in the fuel supply line, a valve in said connection, the :lastmamed valves being disposed adjacent the valve of 1 the air supply line, the valves of the air and fuel supply lines being normally open to supply air and fuel to the chamber tosupport combustion therein during a chamber-heating operation, the Valve of said connection 15 being normally closed, a single member having means to o peratively engage all of said valves and reverse the positions thereof, and electro-magnetie thermostatically-controlled means foreractuating said member.

20 FREDERICK J. RYAN. 

